To prank your friends with a scary screaming face that pops up, convince them to play the Scary Maze Game or convince them to participate in the Can You See It Challenge on Partiers.com. Additionally, TekZoned.com has a Spot the Difference game that results in a scary face popping up at the end.
To prank your friends, have them visit PlayScaryMazeGame.net or send them the link. The game is disguised as a normal maze game that progressively becomes more difficult, forcing players to focus more on the game. Once the player fails the maze, a scary face pops up and screams.
Partiers.com has a "Can You See It Challenge" that you can scare your friends with. The game's objective is to have viewers observe a photo of the woods to see if they can spot anything unusual. A face pops up and screams after they have observed the photograph for a while. TekZoned.com has a similar idea in its "Two Photos - Find the Difference" game. Get your friends to try to find differences between both photos. After a short period of time, a scary face pops up.
YouTube.com has a video titled Ghost Chair that is supposed to seem like a paranormal video of a ghost sitting in a rocking chair. Tell your friends to type "ghost chair" in the search bar and watch the video in the first result as of 2015. A screaming face appears after observing the chair for awhile.